A lot of people seem to be very confused about what 1.0 zoom (1:1 hip-fire) sensitivity means in different games.
4:3 based Source Engine games use 1.0 zoom at 75% monitor match, or a 1.33 coefficient. Translated to Overwatch's Widowmaker Scoped sensitivity, this would be 43.67. The reason why some of the Overwatch Pros use 44, is because they're from CS, and 44 is equal to one click on an AWP. Their value should be changed to 43.67 after the decimal update, but most pros know very little about this stuff, and they can adjust. If they went back to CS however, they would whiff head shots until they re-adjusted.
If you are not from Counter-Strike or Quake, then 1.0 will feel too fast. You won't be used to it. If you are from Call of Duty or Battlefield and used to USA, you need to convert your scopes using 0% match. This equates to 37.89 Widowmaker, and is 1:1 hip-fire in those games.
Your 1:1 is entirely dependent on what scoped sensitivity you are looking to preserve in the new game. Use what YOU are used to.